Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Message-ID: <cedb1604-e024-2738-5b33-15703a653803@gmail.com>
Date:   Tue, 15 Feb 2022 03:46:18 +0900
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Thunderbird/91.6.0
Subject: Re: [BUG] mtd: cfi_cmdset_0002: write regression since v4.17-rc1
Content-Language: en-US
To:     Ahmad Fatoum <a.fatoum@pengutronix.de>,
        Thorsten Leemhuis <regressions@leemhuis.info>,
        linux-mtd@lists.infradead.org, Joakim.Tjernlund@infinera.com,
        miquel.raynal@bootlin.com, vigneshr@ti.com, richard@nod.at,
        "regressions@lists.linux.dev" <regressions@lists.linux.dev>
Cc:     Chris Packham <chris.packham@alliedtelesis.co.nz>,
        Brian Norris <computersforpeace@gmail.com>,
        David Woodhouse <dwmw2@infradead.org>, marek.vasut@gmail.com,
        cyrille.pitchen@wedev4u.fr,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        linuxppc-dev@lists.ozlabs.org
References: <b687c259-6413-26c9-d4c9-b3afa69ea124@pengutronix.de>
 <dff2abcc-5813-2f2c-35ba-f03cd1f35ac3@leemhuis.info>
 <e11b76dc-5539-fb7e-da1c-a5005713d6b0@gmail.com>
 <3dbbcee5-81fc-cdf5-9f8b-b6ccb95beddc@pengutronix.de>
 <0f2cfcac-83ca-51a9-f92c-ff6495dca1d7@gmail.com>
 <b231b498-c8d2-28af-ce66-db8c168047f7@pengutronix.de>
 <66ee55d9-4f20-6722-6097-e53c2108ea07@gmail.com>
 <579eab10-594c-d6b2-0ddb-ea6ab8e02856@pengutronix.de>
From:   Tokunori Ikegami <ikegami.t@gmail.com>
In-Reply-To: <579eab10-594c-d6b2-0ddb-ea6ab8e02856@pengutronix.de>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

Hi Ahmad-san,

On 2022/02/15 1:22, Ahmad Fatoum wrote:
> Hello Tokunori-san,
>
> On 13.02.22 17:47, Tokunori Ikegami wrote:
>> Hi Ahmad-san,
>>
>> Thanks for your confirmations. Sorry for late to reply.
> No worries. I appreciate you taking the time.
>
>> Could you please try the patch attached to disable the chip_good() change as before?
>> I think this should work for S29GL964N since the chip_ready() is used and works as mentioned.
> yes, this resolves my issue:
> Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Thanks for your testing. I have just sent the patch to review.
>
>>>>> Doesn't seem to be a buffered write issue here though as the writes
>>>>> did work fine before dfeae1073583. Any other ideas?
>>>> At first I thought the issue is possible to be resolved by using the word write instead of the buffered writes.
>>>> Now I am thinking to disable the changes dfeae1073583 partially with any condition if possible.
>>> What seems to work for me is checking if chip_good or chip_ready
>>> and map_word is equal to 0xFF. I can't justify why this is ok though.
>>> (Worst case bus is floating at this point of time and Hi-Z is read
>>> as 0xff on CPU data lines...)
>> Sorry I am not sure about this.
>> I thought the chip_ready() itself is correct as implemented as the data sheet in the past.
>> But it did not work correctly so changed to use chip_good() instead as it is also correct.
> What exactly in the datasheet makes you believe chip_good is not appropriate?
I just mentioned about the actual issue behaviors as not worked 
chip_good() on S29GL964N and not worked chip_ready() on 
MX29GL512FHT2I-11G before etc.
Anyway let me recheck the data sheet details as just checked it again 
quickly but needed more investigation to understand.

Regards,
Ikegami

>
> Cheers,
> Ahmad
>
>